Study explores link between presence of cataract and depressive symptoms and lower cognitive function
The presence of cataract was examined as a possible risk factor for depressive symptoms and for lower cognitive function, it has been reported in a large-scale Irish study.
“Cataract is common, with previous studies in Western Europe estimating prevalence at 30% of over 65-year-olds, with a further 10% in this age group having had prior cataract surgery. Cataract has been associated with depression in several epidemiologic studies, a link which was reiterated in our own study,” said Clare Quigley MD, Mater Misericordiae University Hospital, Ireland.
Dr Quigley’s study included 8,146 adults over the age of 50 enrolled in The Irish Longitudinal Study on Ageing (TILDA), a nationally representative longitudinal study of ageing in Ireland. The breakdown was 54% female and 46% male, with a mean age of 64 years. The presence of cataract was reported as present in 371 patients (5% of the total sample), with an additional 513 (6%) being pseudophakic.
Predictor variables, measured at baseline, included self-reported cataract and prior cataract surgery; participants who reported presence of other vision problems, including glaucoma and age-related macular degeneration, were excluded. Other relevant covariates included sex, age, place of birth in Ireland versus elsewhere, polypharmacy (use of four or more medications), and self-reported visual impairment.
Outcome variables included symptoms of depression, assessed via the Center for Epidemiologic Studies Depression (CES-D) scale, at baseline and two years later, and cognitive function, assessed via The Mini- Mental State Exam (MMSE) at baseline only, said Dr Quigley.
While the presence of cataract was associated with significantly higher depressive symptoms at baseline and at follow-up two years later, the association was removed after adjustment for relevant covariates. Other variables significantly associated with depression score at baseline and two years later included positive association with female sex, visual impairment, and polypharmacy, and inverse association with age and place of birth in Ireland.
Cataract was also associated with lower cognitive function in unadjusted analysis at baseline and at follow-up two years later, but this association was removed after adjustment for covariates.
“Pseudophakic, versus phakic, status of study participants did not show strong evidence of association with depression, or cognitive function. Unfortunately, we could not determine an effect of cataract surgery, as we did not follow depression score in participants before and after surgery. This could be an area for further research,” said Dr Quigley. “The fact that the presence of cataract was lower than previous studies may be due to self-reported nature of the data, said Dr Quigley.
“The strengths of the study were a large sample, and that multiple variables were assessed, while the weaknesses were the likely underestimation of cataract incidence, and the lack of visual acuity data or slit lamp examination,” she said.
Dr Quigley said the study picked up a signal which may be important, as with our currently ageing society, the burden of cataract is increasing. “An association with increased depressive symptoms is troubling. Recently, on 30th March 2017, the World Health Organization (WHO) described depression as the leading cause of ill health and disability worldwide,” said Dr Quigley.
“Previously, studies have found an association of lower mood with presence of cataract. However, our analysis is the first to show this in a nationally representative cohort. The advantage of a large-scale study such as ours is that a positive association is drawn from a diverse sample, showing likely importance. One disadvantage is the lack of detail,” she said.
“It would be very useful to determine why those with a diagnosis of cataract had more depressive symptoms; so far we know that it is partially, but interestingly, not fully driven by vision-related quality of life. Especially we want to determine what effect cataract surgery has, as this could be hoped to ameliorate mood problems. Prior prospective studies have shown either no change in mood, or a small improvement. Further research, which examines in more detail what underlies the association, and examines the effect of surgery, are needed,” said Dr Quigley.
A shorter version of this article was published on www.eurotimes.org in April 2017. This article has been updated.
Clare Quigley: firstname.lastname@example.org